1. Field of the Invention
The present invention relates to a method of manufacturing semiconductor films and semiconductor devices and, more particularly to a method of manufacturing thin film insulated gate field effect transistors consisting of polycrystal semiconductor films.
2. Description of the Prior Art
Conventional polycrystal semiconductor devices utilize polycrystal semiconductor films obtained by thermally crystallizing at 550.degree. to 650.degree. C. for several to several tens hours single-crystal semiconductor films deposited by low pressure CVD or plasma CVD. However, it is difficult to form a uniform non-single crystal semiconductor film on a large surface of a substrate by low pressure CVD. And it takes much time to form a non-single crystal semiconductor film by plasma CVD.
Sputtering on the other hand is excellent in this sense. Particularly, there are following advantages when films are deposited by magnetron sputtering.
1) The surfaces of substrates are less damaged by high energy electrons since the electrons are confined in the vicinity of the target.
2) Wide areas can be coated at lower temperatures at a high deposition rate.
3) No dangerous gas is used so that safety process and practicability are ensured.
The sputtering is carried out without hydrogen because the electric characteristics of amorphous semiconductors deposited by sputtering in an atmosphere comprising hydrogen are not so good. The semiconductor films deposited by the sputtering, however, have a disadvantage that thermal crystallization thereof is very difficult due to existence of microstructure in the semiconductor films, that is, due to maldistribution of silicon atoms or the like.